Denial of Service Vulnerability in Cisco Identity Services Engine

CVE-2025-20343

What is CVE-2025-20343?

CVE-2025-20343 is a Denial of Service (DoS) vulnerability found in the Cisco Identity Services Engine (ISE), a robust network administration software designed for identity and access control management. This vulnerability arises from a logic error when the system processes RADIUS access requests associated with MAC addresses already deemed rejected. An attacker can exploit this flaw by sending a crafted sequence of RADIUS requests targeting the vulnerable system. By doing so, they can trigger an unexpected restart of Cisco ISE, which jeopardizes network availability and disrupts services reliant on this critical infrastructure. This can significantly affect an organization's operational capabilities, leading to downtime and potential disruptions in user authentication processes.

Potential Impact of CVE-2025-20343

1. Network Downtime: Successful exploitation can cause the Cisco ISE to restart unexpectedly, leading to a denial of service. This results in significant downtime, affecting all users and devices relying on network access and authentication.

2. Authentication Failures: With the Cisco ISE being integral to identity and access management, a DoS condition can prevent users from accessing necessary resources. This can disrupt business operations, leading to productivity losses and frustration among users.

3. Increased Attack Surface: The ability of an attacker to trigger a DoS condition highlights potential flaws in network defenses. This could encourage further attempts to exploit the system or expose other vulnerabilities, increasing the overall risk profile of the organization.

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